Concrete walls are presently being prefabricated as a way to avoid the time consuming and labor intensive process of building walls with cinder blocks or pouring concrete at a construction site. By use of prefabricated concrete walls, the construction of a wall at the construction site is no longer linked to the amount of manpower available because the labor involves only installation of the previously manufactured wall. Additionally, the cost of the wall is relatively unrelated to the size of the wall.
Generally, the manufacture of a prefabricated concrete wall involves use of a casting bed that includes a set of channel members oriented in a horizontal plane. The channels are arranged in parallel, and the channels include precut notches on their innermost walls. These notches are used to support previously manufactured concrete studs which are set in the horizontal plane perpendicular to the parallel channels. A typical spacing for the notches is two feet center to center.
The channel members and frame sides joining the ends of the channel members are constructed so that the peripheral edges of the grid formed by the studs and the channels, that is, the edges forming an outside rectangle, are higher than all the other members by approximately four inches to form a frame around the entire structure. The parallel channel members which form the support for the concrete studs include cavities of considerable volume which are eventually filled with concrete to encase the ends of the concrete studs which are set into the notches in the channels with the ends of the studs extending into the cavities.
Before concrete is poured into the casting bed, sheet insulation is laid over the concrete studs and impaled upon fasteners cast into and protruding from the concrete studs, and wire reinforcing mesh is laid atop the sheet insulation, but the sheet insulation is sized so that it does not cover the cavities of the channel members.
The wall is then completed by pouring concrete into the casting bed so that it covers the insulation, the wire mesh, and fasteners protruding through the insulation, and fills the cavities in the channel members. The concrete is poured to the height of the top of the outer frame members, and once hardened, not only forms an integral exterior surface, but also bonds together the studs, the insulation, and the top and bottom support beams which are formed in the channel members. The final step of manufacture includes lifting the hardened concrete wall from the casting bed.
This method of making a concrete wall structure is undesirable though due to the length of time required for construction and low insulating values. While sheet insulation is laid over the concrete studs, this relatively thin layer of insulation does not offer adequate insulation properties. Additionally, the wire mesh does increased structural strength of the concrete wall, however, a rebar support member or the like would add even greater structural strength. Accordingly, it is desirable to provide an improved method for making a concrete wall that is quicker to manufacture and has increased insulation properties and increased structural integrity.